2021 Washington State Energy Code (WSEC) Compliance Services

The 2021 WSEC, effective March 15, 2024, is based on the 2021 International Energy Conservation Code (IECC) with Washington-specific amendments. It applies to residential buildings including single- and two-family homes, townhouses, and low-rise multifamily (Group R-2/R-3 up to three stories with direct exterior access).

Key goals: Reduce energy consumption by 70% from 2006 baselines by 2031, promote all-electric systems like heat pumps for decarbonization, and enhance building efficiency through better insulation, air sealing, and mechanical systems. While it favors electric heat pumps (lower carbon credits needed), fossil fuel options are allowed with additional efficiency measures.

Compliance paths include:

• Prescriptive Path: Meet minimum R-values, U-factors, and other specs in Sections R401–R404, plus additional credits from Section R406.
• Performance Path: Use simulations to show equivalent or better energy use.
• Credits System: Mandatory additional measures (e.g., 5–9 credits based on home size) for envelope upgrades, efficient HVAC, renewables, etc.

This code is among the nation's most progressive, emphasizing demand flexibility and greenhouse gas reductions under Washington's Climate Commitment Act.